AoI-aware scheduling has been under intensive research over the last few years.
The works [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]} consider a sufficient power source
whereby an update can be sent any time.
Differently,
[8]}, [9]}, [10]}, [11]}, [12]}
consider that the source nodes are powered by energy harvested from the environment; thus, AoI-aware scheduling is carried out under the energy causality constraint at the source nodes.
Also, while the above works (implicitly) assume that time-sensitive information
is needed at the destination at all time moments, [13]}, [14]}, [15]}, [16]}, [17]}, [18]}, [19]}
study the information freshness of the source(s) driven by users' requests.
